1. Field of the Invention
This invention is directed to security hardware, and in particular to a door lock furniture system, including lock and jamb fittings and their method of installation.
2. Description of the Prior Art
Conventional lock furniture for doors consists of the hardware that is fitted to the door for securing it, and comprises a latch assembly containing a movable latch portion within an elongated housing, which assembly is inserted into a recess in the door edge; and outer and inner actuator portions secured to the outer and inner faces of the door, which are assembled to the door, by insertion into respective outer and inner portions of a through-bore located adjacent the door edge, and which intercepts the latch assembly. A pair of elongated securing screws, inserted form the door inner side through the inner actuator portion, are screwed into projecting post portions of the outer actuator portion, serving to draw the two actuator portions together in mutually securing, aligned relation. In the case of a door furniture assembly having two door handles, the actuator portions each includes a handle portion, the handle of the outer actuator portion including a keyhole to receive a door key; the inner handle portion being axally movable, or possessing a relatively rotatable handle portion, by means of which respective movements the lock can be engaged or disengaged by a user located inside the door.
The door key usually serves only to unlock the latch, thus permitting the opening of the door by way of either of the two handles.
In the case of a deadbolt installation, the lock outer actuator portion usually consists of a key boss, having a keyhole to receive a door key; the inner actuator portion consisting of a boss having a rotatable latch handle, to operate the deadbolt from inside the door.
With a deadbolt type lock, the key is operable to unlock, and also to apply the lock. The reliance upon a pair of screws to hold door lock furniture in secure assembled relation represents a point of weakness in the system, because such screws are subject to backing off, i.e. to unscrew themselves, so as to become slack. In some instances this has even led to complete disengagement of one or both of the screws, with the door handle pulling free from off the door.
In the matter of installation, the securing screws present two problems. First, it is most difficult to align the elongated securing screws with the internally threaded bossed into which they must be threaded, due to their length and an absence of visual alignment, and any slackness in fit of the furniture within the through bore of the door. Also, in the case of a door handle assembly, the inner door handle usually overlies the securing screws, thus denying unobstucted, aligned access to the screw heads, which further impedes alignment of the screws, while also making it necessary to tighten the screws from an awkward, off-centre, misaligned position.